1. Field of the Invention
This invention relates to a process for the preparation of a combustible gaseous mixture (product gas) from a non-gaseous fuel, using a gasifier of the type comprising a rotatably driven cup-shaped divergent support grate constructed as a body of revolution, wherein a granular or pulverized refractory auxiliary material and the fuel are continuously fed to the inner side of said rotating grate, a gasification medium (the process gas) is fed to the outer side of the grate, and the resulting product gas and the exhausted auxiliary material with ash from the fuel are discharged separately from the gasifier.
2. Description of the Prior Art
A process of this kind is disclosed in U.S. Ser. No. 476,205 filed on Mar. 17, 1983 in the name of the present Applicant (assignee: Thomassen International B.V.).
In this known process, the auxiliary material used forms a bed which, as a result of the angle of inclination of the inner side of the support grate and the influence of centrifugal force, gradually slides from the supply point, at the narrowest part of the support grate, toward the peripheral edge at the widest part of the grate. The fuel which is deposited on this sliding bed can then be converted into the required product gas by means of the process gas.
Although this known process gives a satisfactory result for solid fuel and many forms of liquid fuels, difficulties may arise with certain heavy, so-called residual oils, in connection with cracking that causes caking. During the cracking of the said oil the light fractions are separated, so that only the heavy fractions, mainly tar and asphalt, remain. The result is caking on the sliding bed, so that the required gradual displacement of this bed with the fuel resting thereon, is disturbed.